1. Field of the Invention
This invention relates to a two-part mobile telephone configured to be worn about the person, particularly in the manner of a wristwatch.
2. Description of the Prior Art
Portable telephones have become ever smaller and lighter since portable telephones first became widely available for use by the general public. Current portable telephones are very compact and lightweight, and manufacturers are keen to develop telephones which are considered personal accessories, to be carried or worn about the person, rather than separate articles which can be more easily misplaced.
Part of the inspiration for the present invention came from the realization that people are generally accustomed to wearing a watch, and do not generally object to wearing one all day, every day. Indeed, many watches, particularly of the diving or chronograph type, can weigh considerably more than many of the more recent portable telephones. For instance, the Nokia® 8890 telephone weighs 91 g and has a volume of 70 cc, whereas a typical sports or diving watch can weigh well over 100 g. The weight of such watches is often regarded as a sign of quality.
The majority of the weight of such sports watches may be made up of the metalwork of the strap and casing. If the weight of such watches can be capitalized upon, and used instead for functioning circuitry, a telephone can be constructed which the user can wear around his wrist, in the manner of a watch, without noticing any appreciable difference in weight compared with a regular watch.
A wrist-mounted portable telephone is disclosed in co-assigned patent GB 2317300B. In this case, a telephone element 5 is arranged to be detached from a wrist band 2, allowing the user to use the detachable element in the same manner as a regular telephone.
A problem with such an apparatus is the limited volume available in the telephone element 5 itself. The only space available for the battery is in the main body 7 of the telephone 5. Such limited volume restricts the capacity of the battery, which is generally the single bulkiest component of a portable telephone. A limited battery capacity in turn impacts upon the time for which the telephone may be used between charging cycles, causing inconvenience to the user by the frequency of re-charges which are necessary to maintain the telephone in functioning order.